1. Field of the Invention
The invention relates to a piezoelectric vibrator, and more particularly to an improvement in supporting structure of a piezoelectric vibrator having a plate-like piezoelectric element.
2. Description of the Prior Art
The value and importance of improvements for supporting structures of the piezoelectric vibrator having a plate like piezoelectric element are considerable to realize a scaling down of the piezoelectric vibrator and to render the piezoelectric vibrator a light weight as well as to ensure a high reliability of the piezoelectric vibrator.
One of conventional piezoelectric vibrators is disclosed in the Japanese Laid-open Patent Application No. 57-138211 and a structure for supporting the same will be described with reference to FIG. 1.
A plate-like piezoelectric element 21 is accommodated within a cover 23 to be spaced through a gap from an inner surface of the cover 23. Leads 22 are provided to protect from an interior of the cover 23 in an exterior thereof. In the cover 23, the leads 22 are provided at the opposite sides of the plate-like piezoelectric element 21 to be mechanically connected through connecting arms to the plate-like piezoelectric element 21. Namely, the plate-like piezoelectric element 21 is supported through the connecting arms and the leads 22 which are fitted within through holes through which the leads penetrates from the interior of the cover 23 to the exterior thereof.
This conventional supporting structure has a disadvantage in insufficient supporting capability due to the fact that the plate-like piezoelectric element 21 is supported through the connecting arms by the leads 22 which are fixed to the cover 23 but only at the through holes through which the leads 22 are penetrates through the covers 23. Such structure is insufficient for ensuring a high reliability even when the piezoelectric vibrator receives a strong shock. Namely, such structure provides the piezoelectric vibrator with an insufficient shock resistance, resulting in that a mechanical quality factor Qm is lowered.
Another of the conventional supporting structure of the piezoelectric vibrators is disclosed in the Japanese Laid-open Utility Model Application No. 2-5922, which will be described with reference to FIG. 2.
The piezoelectric vibrator comprises a piezoelectric porcelain resonator. A cover 23 made of a silicone rubber accommodates a piezoelectric vibrator 21 and a piezoelectric porcelain vibration plate 24, both of which are securely fined one another and applied with a liquid state insulator such as silicone oil. The united piezoelectric vibrator 21 and the piezoelectric porcelain vibration plate 24 are connected through solder or conductive adhesive 25 to leads 22 which penetrate through through holes of the cover 23 from an interior thereof to an exterior thereof. The leads 22 are fitted within the through holes of the cover 23 and supported only through the fitting faces with the through holes thereof.
Such structure also has a disadvantage in insufficient supporting capability due to the fact that the piezoelectric vibrator 21 and the piezoelectric porcelain vibration plate 24 are are supported through the leads 22 which are fixed to the cover 23 but only at the through holes through which the leads 22 are penetrates through the covers 23. Such structure is insufficient for ensuring a high reliability even when the piezoelectric vibrator receives a strong shock. Namely, such structure provides the piezoelectric vibrator with an insufficient shock resistance, resulting in that a mechanical quality factor Qm is lowered.
Still another of the conventional piezoelectric vibrators is disclosed in the Japanese Laid-open Utility Model Application No. 63-185528, which will be described with reference to FIG. 3. A piezoelectric vibrator 1 is supported by a plurality of projections 27 provided on an inner surface of an armor case 26. Such structure may provide a sufficient capability of supporting the piezoelectric vibrator, however, the piezoelectric may provide a difficulty in vibration of the piezoelectric vibrator 1, resulting in a deterioration of the performance of the vibrator.
It would, therefore, be required to develop a quite novel supporting structure for supporting a piezoelectric vibrator with or without a piezoelectric porcelain resonance having a highly mechanical quality factor and an excellent vibration performance.